Dyes and stain solutions have been used for years, and many of the formulations have not been improved since their initial development. This is particularly true for biological dyes and stain solutions which are used to study plant and animal tissues. One of the problems often encountered with biological stains and dyes regards their stability in solution. In many formulations dye instability is due to variability of the dye components. In other cases, the instability is due to the solvent system.
There has been much interest in recent years in Wright Stains (Romanowsky Stains). In addition to having recently understood the chemical composition of this stain system, workers have attempted to stabilize the system (i.e., prevent the active ingredients from precipitating from solution) by using various approaches. One approach was to use low molecular weight alcohols (eg, methanol, ethanol) and glycerols to solubilize the dye solids and keep them in solution. However, these solvents tend to promote the oxidation of the dyes, which in turn leads to less soluble decomposition products and resulting solution deterioration. Other solvents used have included glycerol, propylene glycol and ethylene glycol monomethyl ether. Many of these solvents are extremely hazardous (i.e., flammable, extremely toxic and possibly teratogenic). As a result, there are many negative aspects involved with using these materials. In addition, although they may stabilize the system to some extent, they fall short in providing the needed stability for a commercially feasible, long shelf life system. The current invention eliminates all of the above problems, and it has been found to provide the needed benefits for Romanowsky and a number of other dye and stain systems.